Electron discharge device



July 18, 1950 A. v. HAEFF 2,515,998

ELECTRON DISCHARGE DEVICE Original Filed April 24, 1942 5 Sheets-Sheet l -INVENTOR mm b Y .July 18, 1950 A. v. HAEFF Q 2,515,998

ELECTRON DISCHARGE DEVICE Original Filed April 24, 1942 3 Sheets-Sheet 2 I r 4 0 1 W) 3 7 1 l 46 47 ME 7/ 5 37 35 I I I I II I kl. J 1

T l l l INVENTOR Patented July 18, 1950 ELECTRON DISCHARGE DEVICE Andrew V. Haeif, Washington, D. 0., assignor to Radio Corporation of America, a corporation of Delaware Original application April 24, 1942, Serial No.

440,297, now Patent N 0. 2,433,044, dated Decemher 23, 1947.

Divided and this application November 19,1947, Serial No. 786,905

4 Glaims. 1

My invention relates to electron discharge devices, more particularly to such devices utilizing electron beam deflection and useful at ultra high frequencies.

This application is a division of my copending application Serial No. 440,297, filed April 24, 1942, now U. S. Patent No. 2,433,044, dated December 23, 1947, and assigned to the same assignee as the present application.

' In conventional tubes utilizing beam deflection, abeam of electrons is directed from the cathode between a pair of deflecting electrodes toward an apertured electrode behind which is placed an electron collector. Alternating radio frequency voltages are applied to the deflecting electrodes to cause theelectron beam to he deflected across the apertured electrode, thus to control the amount of current to the collector, which may be used as an output electrode, In such types of tubes the deflection sensitivity drops ofi as the frequency at which the tube is operated is increased, that is, the transconductance of the tube decreases. Tubes of this kind are also subject to the limitation of the usual conventional tubes in that when operated at ultra high frequencies the presence of considerable loading in the input circuit results in an excessive amount of power being required to drive the tube. This decreases the effective power gain of the tube when operated as an amplifier.

Fundamental causes of high input loading are, among other things, ohmic and radiation losses due to high circulating currents in electrodes and leads. Electron loading also results from the interaction of the electron stream and the circuits connected to tube electrodes, and may include degenerative or regenerative effects caused by common lead impedances.

It is an object of my invention to provide an electron discharge device of the beam deflection type which is particularly suitable for use at high frequencies and which has a comparatively high transconductance.

It is another object of my invention to provide such a device utilizing an input circuit in which input loading is minimized, thus making more eifective use of the driving power.

A still further object of my invention is to provide an electron discharge device of the beam deflection type useful at ultra .high frequencies and which employs low loss input and output electrode systems and circuits.

A further object of my invention is to provide such a device in which undesired coupling, due to common leads and ineffective shielding, is reduced to a minimum.

Another object of my invention is to provide an electron discharge device of the beam deflecamplifier, oscillator or a mixer.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. l is a schematic longitudinal section of an electron discharge device made according to my invention and its associated circuit, Fig. 2 is a perspective, partly in section, of the electrode system utilized in the device shown in Fig. 1, Fig. '3 a schematic longitudinal section of a modification of an electron discharge device made according to my invention and its associated circuit, Fig. 4 is a perspective, partly in section, of the output tank circuit utilized in the electron discharge device shown in Fig. 3, and Figs. 5, 6 and 7 are schematic longitudinal sections of other modifications cf my invention.

As shown in Fig. 1, an electron discharge device made according to my invention comprises an envelope t0 having at one end a cathode ll, which may be indirectly heated, and a pair of accelerating and focusing electrodes 12-43, and at the other end acollector' it for receiving electrons. In accordance with my invention, I position between the focusing electrode and the collector a resonant cavity tank circuit or resonator l5 having a pair of oppositely disposed deflecting elements l t-ll positioned adjacent to and elece trically connected to and supported by opposite walls of the cavity adjacent the apertures 26 and El. Positioned between the resonant cavity-and the collector is the conductingplate-li-ke member l8 having an elongated aperture 19 and centrally positioned a conducting rod 20 for thus providing a double aperture. Preferably the length of the overlapping portions of the deflecting elements it and ll is equal to the distance travelled by an electron during a half period of the applied controlling voltage While the tube is in operation. It has been found that this provides maximum deflection sensitivity.

A biasing divider arrangement for the deflecting electrodes is shown at El and the output is taken between collector it and apertured conducting member it by means of the output trans former 24. Voltage sources for the various e1ectrodes are shown at 25. The input coupling loop 22 within the resonator I5 is connected to a 'coaxial transmission line '23.

In operation, the biasing or polarizing voltages are applied to electrodes l2-l3 to focus and properly :direct electrons through the elongated aperture of the resonant cavity tank circuit I5. In passing through the resonant cavity the beam is subjected to a transverse alternating field between the elements I5 and I! and deflected across apertured element I8, the electrons being collected at I4, the double aperture in element I8 giving a desired control voltage-anode current characteristic.

The resonator is maintained energized by means of the input line 28 and coupling loop 22. In one mode of excitation an electromagnetic field is set up within the cavity such that the magnetic lines of force are approximately concentric with and coaxial with the cavity. The radio frequency currents circulate alternately from one side of the inner surface of the cavity to the other between the apertures, causing each of the deflecting elements I9 and IT to receive a voltage thereon approximately equal to the voltage appearing at the aperture adjacent which the element is connected, so that the electron stream is subjected to a deflecting electric field.

In the modification shown in Fig. 3 which utilizes a push-pull output resonator, the input circuit is substantially the same as that shown in Fig. 1. Mounted at one end of the envelope of which the resonators form part is an elongated cup-shaped insulation member 29 enclosing cathode 30, accelerating or modulating grid 3|, and focusing and accelerating electrodes 32 and 33, the cup-shaped member being fused to the collar M of the resonant cavity tank circuit 38. The resonant cavity tank circuit is energized by means of coupling loop 42 so that a deflecting voltage appears across electrodes 39 and 40 as explained above. Following this resonant cavity 38 is a beam-directing and separating electrode system housed within the insulating collar portion 44 fused to the collar 43 of resonator 38 and collar 51 of resonator 48. Electrode 4'! maintained at a lower potential than the accelerating and directing electrodes 45 and 46 insures that the beam is directed into one or the other of the two passageways provided in the resonant cavity 48. The resonant cavity 48 is provided with reentrant tubular extensions 49 and 50 separated by gap 5|, and 52 and 53 separated by gap 54, the output being taken by means of coupling loops 55 and 56. A collar 58 supports a collector system comprising cup-shaped members 3435 having mountedtherein secondary electron suppressors 36 and 31, the envelope being sealed by means of the plate 59, supporting members 34 and 35.

The modulating circuit II may be utilized to modulate the stream before entrance of the beam into the deflecting resonator, or it may be utilized simply as an accelerator. The biasing voltage and divider source is shown at 69 for biasing and focusing electrode elements 32 and 83. As in the first case, the beam of electrons is deflected in passing between electrodes 39 and 49 so as to pass between electrodes 4! and 46, or 45 and 41, and in passing across either of the gaps 5| or 54 excites the resonant cavity 48. In the mode of oscillation utilized, each half of the resonator oscillates at a phase difierential of 180 with respect to the other half so that the beam will always be decelerated in passing over gap 5| or gap 54 to maintain the resonator energized. This results in a push-pull output which can be extracted by means of the coupling loops 55 and 50. The manner in which the resonator 48 is caused to be energized by inductive action is now well understood and is described in my earlier Patent 2,237,878, issued April 8, 1941.

In the modification shown in Fig. 5, I utilize a double cavity for successively extracting energy from the beam passing through this cavity. The insulating cup-shaped member 89-contains cathode BI and grid 82, as well as the focusing and accelerating electrodes 83 and 84. The electron beam again passes through the deflecting resonant cavity tank circuit 85 driven by coupling loop 88 and having deflecting electrodes 88 and 81 through which the beam is directed and by which the beam is deflected. The beam is directed either between electrodes 99 and 92 or 9| and 92 positioned within the collar member 89. Electrodes 99 and 9| act with the electrode 92, which is the separating electrode held at a potential lower than electrodes 99 and 9|, to direct the beam through one or the other of the two paths through the output resonant cavity tank system 93. This system comprises a pair of cavities 94 and 95 having reentrant portions 96, 91, I04 and I05 and having a separating chamber formed by partitions I09, IOI having passageways I00 and IOI' extending therethrough. The resonant cavities are energized when the beam passes gaps 98 and I02 and 99 and I03. Energy is extracted from the resonant cavity tank circuits 94 and 95 by means of coupling loops I01 and I08 and the electrons collected by means of the cup-shaped member I08. The modulating circuit is shown at I01 for the grid, and the voltage divider and voltage source I98 is provided for accelerating electrodes 03 and 84. A voltage source I09 provides the necessary voltages for other electrodes and the voltage divider system IIO permits adjustment of the voltage on the beam directing electrodes 90, 9| to properly insure that the beam will travel through the proper passageway. Cavities 9495 are separate and distinct and separated by the apertured partitions I00 and IOI, the transit time of the electrons being matched to the output system such that the electrons are subjected to a decelerating field at gaps 98 and I02, and 99 and I03 in passing through the output system. This requires that the transit time of the electrons through elements I00 and I 0| be equal to approximately one-half period, assuming that resonant cavity tank circuits 94 and 95 are operating 180 out of phase. Of course this arrangement need not be used and the electron transit time through I00 and IOI can be made more or less if a difierent phase relationship is desired between the voltages induced in cavities 94 and 95. The mode of oscillation for each of the cavities 94 and 95 is the same as for cavity 48 in Fig. 3.

In the modification shown in Fig. 6, I employ a push-pull system in the output utilizing a lecher wire arrangement and a double anode or collector 4 system. In this arrangement envelope III has at one end cathode II 2, accelerating grid I I3 and accelerating and focusing electrodes I I4 and H4. The resonant cavity H5 is driven by coupling loop I I8 and is provided with deflecting electrodes H6 and Ill. Electrons are directed into the shielded output system comprising anode electrodes I20 and |2I connected together by lecher wire system II9, the separating electrode I24 being maintained at a lower potential than electrodes I20 and I2I and lecher wire system II 9. This whole arrangement is shielded by means of shielding compartment I22 and energy inductively extracted by means of coupling loop I25. The voltage sources for properly biasing or polarizing are shown at I26, I 21 and I28. Since electrodes I 20 and I2I operate out of phase, the deflection of the electron beam from one to the other of these two electrodes can be properly phased to drive the output system.

In Fig. 7 I show a still further modification of my invention utilizing a doubly decelerating output circuit mounted within a cavity. Here envelope I30 has mounted at one end cathode I3l, accelerating electrode I32 and accelerating and focusing electrodes I33 and E34. The resonant cavity I35 driven by coupling loop I38 is provided with deflecting electrodes I36 and IE7 for bringing about a deflection of the beam generated by the cathode electrode system.

The output system comprises the enclosing conducting structure I39 provided with reentrant portions I42, Ml, I43 and M8, which with the tubular electrodes I40 and MI provide a double set of gaps M5 and I46, and I40 and I50, the separating electrode I63 extending through the bottom of the envelope and being maintained at a lower potential than the conducting enclosure and the elements within the enclosure. The beam in passing, for example, through the tubular member I40 to the collector I6I is subjected to a double deceleration, giving up energy at gaps M5 and I45 in a manner noW well known and in accordance with the principles set forth in my patent above referred to. Since the tubular elements I00 and MI extract energy from the stream 180 out of phase with each other, they may be properly coupled by means of loop I64, which in turn is coupled to output loop H65 extending through envelope I30 and within conducting member I39. Thus, this latter arrangement provides a push-pull double decelerating device in combination with a resonant cavity circuit system for deflecting the electron beam.

In all arrangements above described the input circuit which comprises the resonant cavity tank circuit or resonator is a circuit of low, loss both from the standpoint of resistance and radiation losses. Loss of deflection sensitivity due to design of the deflecting electrodes is at a minimum and the output and input circuits because of the enclosed fields are completely shielded from each other and because of the absence of common leads there is substantially no reaction or interaction between the input and output systems. If desired, the forms shown in the figures couldbe utilized as well for mixers by applying a local oscillator voltage, for example, either to the grid electrodes 3| and 82, as shown in Figs. 3 and 5, or both local oscillator and signal voltage could be applied to coupling loops 42 and 88, for example. In either case both voltages could be utilized for bringing about intermediate frequency voltages in the output system.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated only one specific application for which my invention may be employed, it will be apparent that my invention is by no means limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention as set forth in the appended claims.

What I claim as new is:

1. An electron discharge device having a cathode electrode means for providing a beam of electrons, a cavity resonator having oppositely disposed apertures through which the path of said beam lies, deflecting electrodes positioned within the cavity resonator and supported from and electrically connected to opposite Walls of the cavity resonator adjacent said apertures, whereby the path of said beam of electrons passes between said deflecting electrodes, and an output electrode system for receiving said beam of electrons including a pair of oppositely disposed collectors between which said beam of electrons is deflected and a Lecher wire system connected to said collectors.

2. An electron discharge device having a cathode electrode means for providing a beam of electrons, a cavity resonator having oppositely disposed apertures through which the path of said beam is directed, and deflecting electrodes positioned within the cavity resonator and supported from and electrically connected to opposite walls of the cavity resonator adjacent said apertures, whereby the path of said beam of electrons passes between said deflecting electrodes, an output electrode system including a pair of oppositely disposed collectors between which the beam of electrons is deflected and a lecher wire system connected to said collectors, and a separating electrode adapted to be maintained at a lower potential than said collectors during operation of said device and positioned between said collectors.

3. An electron discharge device having a cathode electrode means for providing a beam of electrons, a cavity resonator having oppositely disposed apertures through which the path oif said beam is directed, and deflecting electrodes positioned within the cavity resonator and supported from and electrically connected to opposite walls of the cavity resonator adjacent said apertures;

whereby the path of said beam of electrons passes between said deflecting electrodes, an output electrode system including a pair of oppositely disposed collectors between which said beam of electrons is directed and a lecher Wire system connected to said collectors, and a shielding compartment surrounding said collectors and lecher wire system.

4. An electron discharge device having a cathode electrode means for providing a beam of electrons, a cavity resonator having oppositely disposed apertures through which said beam is directed, and deflecting electrodes positioned within the cavity resonator and supported from and electrically connected to opposite walls of the cavity resonator adjacent said apertures, whereby the path of said beam of electrons passes between said deflecting electrodes, an output electrode system including a pair of oppositely disposed collectors and a lecher wire system connected between said collectors, and a separating electrode adapted to be maintained at a lower potential than said collectors duringoperation of said device and positioned between said collectors, and

a shielding compartment surrounding said collectors and lecher wire system, and a coupling loop coupled with said lecher wire system for extracting energy from said output electrode system.

ANDREW V. HAEFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,407,707 Kilgore Sept. 17, 1946 2,407,708 Kilgore 'Sept. 17, 1946 2,433,044 Haeff Dec. 23, 1947 

